1. Field of the Invention
The present invention relates to a composite connector to which a digital signal or an analog signal is transmitted, and to an electronic apparatus including the composite connector.
2. Description of the Related Art
An electronic apparatus is provided with a universal serial bus (USB) connector for communication with a personal computer (PC). An A connector at a PC side (corresponding to a host) and a B connector at an apparatus side are connected to each other with a USB cable, to exchange data. In a small portable electronic apparatus, such as a digital camera or a video camera, a mini-B connector is mounted and used for exchanging photographed images or for exchanging data when directly operating the portable electronic apparatus using the PC. When one wants to print out the photographed images, the portable electronic apparatus is directly connected to a printer. When peripheral devices are connected to each other, a mini-A connector, which is a downsized version of the A connector, may be used. USB signal lines include signal lines D+ and D− and power supply lines VBUS and GND. The signal lines are used to transmit differential signals. Two signal lines are provided for transmitting one signal, to transmit the signal on the basis of a potential difference thereof. In addition, a signal line including an ID signal used in a USB On-The-Go Standard is available. Here, the USB On-The-Go Standard makes it possible to transfer data as a result of directly connecting electronic apparatuses to each other using a USB cable instead of connecting them through the PC.
As an image output terminal, an AV terminal is mounted to a digital camera or a video camera. An AV cable is connected to a monitor or an audio device to output an image or a sound.
Since, for example, the shape of a USB cable plug differs from the shape of an AV cable plug, receptacle connectors are disposed in correspondence with the respective plugs in the apparatus. However, the volume occupied by the USB connector and an AV connector in the apparatus is large. This is a serious hindrance to reducing the size of the electronic apparatus. Accordingly, a technology which makes it possible to insert the mini-A connector and the mini-B connector into one connector is disclosed in Japanese Patent Laid-Open No. 2007-59351.
Data transfer speed of the USB tends to increase. USB2.0 has Hi-speed, Full-speed, and Low-speed communication modes. In the Hi-speed communication mode, high-speed communication is performed at 480 Mbps. A characteristic impedance required of a USB transmission path is equal to a differential impedance of 90Ω±15%. It is necessary to perform impedance control on a pair of D+ and D− signals (which are USB differential signals). Various considerations need to be made for maintaining communication, such as making the lengths of wires equal to each other for ensuring the quality of signals, and adjusting the widths and thicknesses of the wires so that the impedance is set at a prescribed value.
The high-speed differential signals generate radiation noise as a result of moving in a board, a connector, or a cable. The noise generated from a circuit in another apparatus may be transmitted along the USB cable or the AV cable and radiated to the outside. Therefore, the influence of radiation noise on other apparatuses is becoming a problem. To overcome this problem, a common mode choke coil is inserted in the USB differential signals or a bead is inserted in audio and video signal lines.
However, when a connector in which two types of plugs can be inserted is used, different signal lines for USB signals and AV signals are mixed, thereby making it difficult to overcome radiation noise and to maintain the quality of the signals.
FIG. 14 is a rear perspective view of a conventional connector. Reference numeral 400 denotes a connector in which two types of plugs can be inserted. Terminals are drawn out for mounting the connector 400 to a wiring board from the rear side of the connector. In FIG. 14, USB signals move at the upper side; and other signals, such as AV signals, move at the lower side. USB signal lines are drawn out straight, and lower AV signal lines are bent toward both sides and drawn out. An arrangement of pins at the upper USB side is prescribed on the basis of a USB standard. Reference numeral 401 denotes USB signal terminals, reference numeral 402 denotes a USB GND terminal (USB ground terminal), reference numeral 403 denotes an ID terminal, reference numeral 404 denotes a D+ terminal, reference numeral 405 denotes a D− terminal, and reference numeral 406 denotes a Vbus terminal. Reference numeral 407 denotes AV terminals, which are disposed at respective sides of the USB signal terminals 401. Since the AV terminals are separated at the respective sides, they need to be disposed on respective sides of the USB differential signals.
In FIG. 15 showing another conventional example, USB terminals 401 are disposed at the upper side, and AV terminals 407 are disposed at the lower side. These terminals are substantially alternately drawn out. In this case, the AV terminals 407 are disposed between a USB differential signal terminal D+ 404 and a differential signal terminal D− 405 on a wiring board. This may influence signals thereof. Japanese Patent Laid-Open No. 2007-59351 does not discuss the quality of the signals and noise.